Large Amounts Of Heavy Metals Research Articles

Comparison study of three universal methods for the recovery and purification of valuable heavy metals from electroplating sludge

The large amount of heavy metals from waste electroplating sludge has great recovery and treatment value, which is of great significance for environmental protection, resource recycling and sustainable development. In actual process, metals were relatively easy to be extracted from sludge, but the separation process was more complex. In this study, three universal methods for extracting low-grade and complex heavy metals from electroplating sludge (actual solid waste sample from Zhejiang Province, China) in terms of Selective ammonia treatment process (SAP), efficient acid treatment process (EAP) and roasting-acid treatment process (RAP) were investigated. In comparison, EAP was more advanced in extracting heavy metals from actual samples than SAP and RAP. It was noticed, by optimizing the separation and purification process, when the acid concentration was 5 % and the liquid–solid ratio was 10:1 with the assistance of effective extractants of Lix984N and P507, the purity and recovery rates for both copper and zinc products could reach to over 90 %, meanwhile, more than 80 % recovery rates of nickel products could be obtained. And compared with some existing related studies, the research process has the advantages of simpler operation mode and better separation effect, which offers the valuable insights into efficient separation and recovery of heavy metal resources from electroplating sludge. The methodology employed in this work can be easily applied to other solid/hazardous waste extraction processes.

Critical assessment and recommendations for sewage sludge management in Poland

The purpose of the article is to demonstrate practices used to supervise the use of sewage sludge for agricultural purposes. The presented research and conclusions are a trend analysis and are not to be used to penalise entities. Sewage sludge, which comes from the illegal dumping of wastewater into municipal wastewater by industrial plants, contains large amounts of heavy metals. Treatment plants transfer the sludge for agricultural use. Regulations specifically restrict the mode and conditions for such use of sludge. Methods: the research was carried out using a proprietary questionnaire, which is a supplement to the reporting questionnaire of the National Urban Wastewater Treatment Program implemented by the State Water Company "Wody Polskie". Results: The survey was conducted at 208 wastewater treatment plants in Poland. The results show that the majority of wastewater treatment plants do not properly supervise the process of introducing sewage sludge into the soil. They also lack supervision of how much heavy metals from wastewater are introduced into the soil. This means that there is a very high risk of contamination of agricultural soils. The results obtained could initiate a detailed analysis of this phenomenon in Poland. A comprehensive study of the scale of the practice and its current effects is required to determine the actual condition of soil treated with sewage sludge.

Toxic metals in water and soil

Industrialization and the development of modern civilization in general brought with it large amounts of heavy metals that were dispersed in the environment. Rapid screening technology for the detection of major and trace elements as well as heavy metals in various environmental samples was the goal of our research in this very topical area from an ecological and human health point of view. In this sense, the objectives of this study were to determine the limits of detection, accuracy, repeatability, selectivity and efficiency of different analytical methods in elemental analysis, especially traces of toxic elements. To assess the state of the environment, it is necessary to carry out a complete analysis of microelements using different analytical methods, as well as the preparation of samples, especially soil. Heavy metals that are extremely toxic are arsenic, lead, mercury, cadmium, chromium, copper and nickel, and given their extremely negative impact on human health, and mutation and lethal outcomes, their concentration in environmental samples must be accurately and precisely measured, especially in its primary components, water, soil and air. The aim of the measurement is to monitor, control and determine the presence of pollutants, but also to identify sources of pollution that threaten the living environment, the living world and, ultimately, humans, the last in the food chain.

Stabilization effect of chelating agents on heavy metals in two types of municipal solid waste incineration fly ash

Municipal solid waste incineration (MSWI) fly ash is complex in composition and contains large amounts of heavy metals. To investigate the effects of different passivating agents on Cd, Pb, Cr, Ni and Zn in different types of fly ash, 7 reagents were selected as passivating agents, including 3 inorganic reagents (Na2S, Na3PO4, NaH2PO4) and 4 organic reagents (SDD, DDTC, TMT, thiourea). The results showed that at low addition levels, sulfur-containing organic chemicals and phosphates were more effective in chelating these metals in both grate furnace incineration fly ash (GF FA) and circulating fluidised bed incineration fly ash (CFB FA), while Na2S was more effective in chelating heavy metals in CFB FA. In addition, agents containing -N-CS groups showed better chelation of heavy metals in GF FA, while heavy metals in CFB FA were more affinity to agents containing -SH groups. The ternary compound TMT-NaH2PO4-SDD (m1:m2:m3 = 2:3:1) was an excellent chelating agent for Pb, Cd in the GF FA, and TMT-Na2S-thiourea (m1:m2:m3 = 2:1:3) was a suitable chelating agent for these metals in CFB FA. The chelation rate of Cd and Pb after the treatments mixed ternary reagents was above 99%, and the leaching amount was much lower than the limit value of pollution control standards for domestic landfills. Moreover, under different pH leaching conditions, the leaching concentrations of Cd and Pb in the fly ashes treated with the ternary mixture were lower than the standard limits. In general, the ternary compound can effectively chelate heavy metals in fly ash, which provides a reference for selecting a suitable stabilizer combination for heavy metal in fly ash.

Comparative Study of Mercury in Canned and Fresh Indian Oil Sardine Sardinella longiceps

Essential and non-essential heavy metals are two categories for heavy metals. Small amounts of essential heavy metals are required by the human body to ensure its proper operation. High concentrations can become hazardous and change how the biochemical mechanisms that keep the human body functioning normally. The human body does not require non-essential heavy metals like mercury (Hg), which can be harmful to human health. Mercury can come from both natural and anthropogenic sources. When polluted soil and organisms are consumed by aquatic species, mercury bioaccumulates in their tissues, and its concentration rises up the food chain. Within the marine ecology, fish are at the top of the food chain. The aquatic food chain often starts with fish, and fish organs and tissues are at the top of the hierarchy and accumulate large amounts of heavy metals. In particular, the liver, kidney, and gill organs store metals (loids) at the highest level, and this varies depending on the type of metal; nonetheless, muscle is extensively examined as it is the main part of fish consumed by people. The muscular tissue of canned and fresh Indian oil sardines (Sardinella longiceps) was examined in the current investigation to determine the buildup of mercury there. Utilising a spectrophotometric analytical approach, stannous chloride was used for the analysis. Mercury levels in canned and fresh sardines were found to be 0.09 and 0.10 ppm, respectively. Sardines have a known Hg concentration of 0.04-0.18 ppm at the non-predator trophic level worldwide, which is also the level at which sardines may be consumed. Thus, the present sardines under study from Mumbai region are found to be suitable for consumption.

Lake Sediment Archive Reveals a Distinct Response to Anthropogenic Pb and Zn Deposition with Historical Periods: Pb-Zn Isotope Evidence.

Anthropogenic activities release large quantities of heavy metals into the atmosphere. In China, the input of these heavy metals through local and trans-boundary atmospheric deposition is poorly understood. To assess this issue, herein, we use Pb and Zn isotopes to constrain the sources of Pb and Zn in a 210Pb-dated sediment core collected from the enclosed lake in South China. We observed a progressive shift toward higher 208Pb/206Pb and Pb fluxes (0.79-4.02 μg·cm-2·a-1) from 1850 to 1950 and a consistent decrease in δ66ZnIRMM (as low as -0.097 ± 0.030‰) coupled with an increase in Pb (1.74-3.36 μg·cm-2·a-1) and Zn (8.07-10.44 μg·cm-2·a-1) fluxes after 1980. These distinguished isotopic signals and flux variations reveal the presence of trans-boundary Pb since 1900, with the addition of local industrial Pb and Zn pollution after 1980. Up to 72.3% of Pb deposited at our site can be attributed to long-distance transportation from previously industrialized countries, resulting in a noteworthy legacy of Pb in China since 1900. Despite the phasing out of leaded gasoline, Chinese gasoline still contributes an average of 20.9%. The contribution of China's mining and smelting activities to Pb has increased steadily since 1980 and remained stable at an average of 25.1% since 2000.

Analisis Pengaruh Kapur Tohor (CaO) dan Tawas Terhadap Parameter TSS dan pH di Desa Huta Dame Kecamatan Penyabungan Utara Kabupaten Mandailing Natal

The people's gold mining activities in Huta Dame Village, Kotanopan Utara District, Mandailing Natal are still very simple. The purpose of this study was to analyze the TSS and pH parameters around the gold mining area so that they comply with quality standards. This research method is by interviews and direct observation to the field. The results of the analysis showed that the quality of acid mine drainage before treatment was 4.26 and after the addition of quicklime in 1 gram it was still acidic but in the addition of quicklime in the 65th minute (3 grams) a pH of 6.02 was obtained and it met the quality standard. The addition of 1 and 3 grams of alum is still acidic and this can cause the air in the mining environment to be corrosive due to the large amount of heavy metals originating from rocks which can cause environmental damage, due to excessive use of mercury resulting in the emergence of acid mine drainage. The addition of 1 and 3 grams of quicklime, TSS values 48 & 38 mg/l . The TSS values for the addition of 1 & 3 grams of alum were 20 & 28 mg/l and met the quality standards. Thus the use of quicklime in gold mining waste is more effective than the use of alum as an acid mine drainage treatment method.

Evaluation of the ability of cement prepared with incineration fly ash to solidify heavy metals at high temperatures

Scholars have demonstrated the feasibility of using incineration fly ash to prepare cement. Therefore, this article evaluated the performance changes and the ability to solidify heavy metals of cement prepared with the incineration fly ash after being exposed to fire (high temperature). The research results indicated that with the increase of incineration fly ash content, the mass loss of the cement prepared rose from 8.96% to 9.92%, and the strength loss increased from 63.91% to 92.73% after high-temperature treatment at 800 °C. Which proved that the incineration fly ash significantly weakened the performance of the cement after high temperatures, which was not conducive to the reuse of the components in cement. After high-temperature treatment, new phases - Lime and Tobermorite were generated, and the pore structure of cement was greatly changed, with a decrease in harmless pores. The content of harmful and multi-harmful pores exceeded 87%. A large amount of heavy metals evaporated, resulting in a decline of heavy metal content in cement. The leaching concentration of a few heavy metals in weak acid environments tended to increase, but it was still far below the limits specified in Chinese standards GB 5085.3-2007, GB 16889-2008, and GB 18598-2019. Therefore, the high-temperature treated cement still effectively solidified residual heavy metals, but it could not suppress the volatilization of heavy metals at high temperatures.

Physicochemical, Biochemical and Genotoxic Profile of Subchronic Exposure of Wister Rats to Treated Crude Oil Exploration Water

Background: Crude oil exploration water is the major waste product generated from petroleum exploration and production activities and is known to be a complex composition of numerous hazardous chemicals, including large quantities of heavy metals, inorganic, and organic substances and naturally occurring radioactive materials (NORMs).
 Objectives: This study was designed to investigate the physicochemical, biochemical and genotoxic profile of subchronic exposure of Wister rats to treated crude oil exploration water (TCOEW).
 Materials and Methods: Fifty rats were randomly assigned to five treatment groups, with ten rats per group, and treated with five concentrations (1%, 5%, 10% and 20%) of TCOEW. Each TCOEW concentration was administered for 90 days ad-libitum as normal drinking water to each group, while the control group was given tap water. Blood, liver, kidney, thymus, spleen and femoral bone of the animals were collected at the end of exposure for biochemical and histological assessments. The pH, conductivity, and turbidity were carried out on-site, while other physicochemical parameters were determined using standard laboratory methods. Data were analysed using descriptive statistics and ANOVA at α 0.05.
 Results: Treated crude oil exploration water caused a significant (p < 0.05) increase in RBC, PCV and Hb while other hematological and biochemical parameters showed no difference. Also, TCOEW cause a significant increase in polychromatic erythrocytes (PCEs) in genotoxicity test and no major lesion were seen in the histopathology studies. Treated Crude Oil Exploration Water does not comply with FEPA standards of produced water due to high conductivity, salinity and total dissolved solid of the sample. The marked increase in micronuclei polychromatic erythrocyte formation (MNPCE) showed that TCOEW might be genotoxic and this could be responsible for the significant increase RBC, parked cell volume (PCV) and hemoglobin (Hb) observed.
 Conclusion: Although TCOEW does not totally meet FEPA standard for effluent discharge, it has mild genotoxic effect.

Phytoremediation of Heavy Metal Contaminated Soils Using Various Flower and Ornamentals

Soil contamination has become a serious problem in many industrialized and developing countries. Indiscriminate dumping of urban and industrial effluents along with solid waste often lead to toxic accumulation of heavy metal ions which not only impair soil productivity but also cause health hazards by entering into food chain via soil-plant-animal/human route. With rapid urbanization and industrialization, large quantities of industrial effluents get mixed with sewage and river water [1]. Irrigating crop fields with such contaminated sewage water is being increasingly adopted by marginal farmers due to scarcity of irrigation water. It also inadvertently leads to addition of large quantity of heavy metals to the agro ecosystem [2]. Plants with abilities to hyperaccumulate, accumulate, exclude and indicate heavy metals are important in environmental remediation. Most phytoremediation studies are aimed at inorganic pollutants through different approaches defined as phytoextraction (the used of metal accumulating plants to transport and concentrate metals from the soil to roots and above ground biomass), rhizofiltration (the use of plant roots to absorb, precipitate, and concentrate toxic metals from polluted effluents), and phytostabilization (the use of plants to reduce the mobility of metals)

Bio-transfer and bioaccumulation patterns of heavy metals in mine site-inhabiting ants and grasshoppers, across mine site restoration chronosequence.

Soil is known to serve as a significant sink for heavy metals in coal mine sites, thus also influence the plant and other organisms of that area. Hence, the presence of heavy metals in coal mine soil is of concern to land managers. Insects occupy different trophic positions in the food chains, thus many insect species accumulate large amounts of heavy metals in their bodies and this is a matter of concern. In the present study, we investigated biotransfer and bioaccumulation of heavy metals from soil, grass species Cynodon dactylon, Vetiveria zizanioides, grasshopper species Gastrimargus africanus, Choroedocus robustus, ant species Cataglyphis longipedem and Camponotus compressus in six different ages (2, 4, 6, 8, 10 and 12 year old) of coal mine sites. Our study revealed that at some extent the heavy metal content and BAF patterns of heavy metals along different pathways (from soil to grass, soil to grasshoppers and from grass to grasshoppers) were not consistent and did not reflect the soil pollution status for all the metals, related to the mine spoil dump age. However, in contrast, ants successfully reflected a consistent pattern in the bioaccumulation of heavy metals via soil, thereby indicating the pollution status of the soil along with the restoration age of mine spoil dumps. Our study showed that ant species can successfully forecast the presence of heavy metals of coal mine spoils along with their restoration.

Responses of rhizosphere microbial community structure and metabolic function to heavy metal coinhibition.

Metal mineral mining results in releases of large amounts of heavy metals into the environment, and it is necessary to better understand the response of rhizosphere microbial communities to simultaneous stress from multiple heavy metals (HMs), which directly impacts plant growth and human health. In this study, by adding different concentrations of cadmium (Cd) to a soil with high background concentrations of vanadium (V) and chromium (Cr), the growth of maize during the jointing stage was explored under limiting conditions. High-throughput sequencing was used to explore the response and survival strategies of rhizosphere soil microbial communities to complex HM stress. The results showed that complex HMs inhibited the growth of maize at the jointing stage, and the diversity and abundance of maize rhizosphere soil microorganisms were significantly different at different metal enrichment levels. In addition, according to the different stress levels, the maize rhizosphere attracted many tolerant colonizing bacteria, and cooccurrence network analysis showed that these bacteria interacted very closely. The effects of residual heavy metals on beneficial microorganisms (such as Xanthomonas, Sphingomonas, and lysozyme) were significantly stronger than those of bioavailable metals and soil physical and chemical properties. PICRUSt analysis revealed that the different forms of V and Cd had significantly greater effects on microbial metabolic pathways than all forms of Cr. Cr mainly affected the two major metabolic pathways: microbial cell growth and division and environmental information transmission. In addition, significant differences in rhizosphere microbial metabolism under different concentrations were found, and this can serve as a reference for subsequent metagenomic analysis. This study is helpful for exploring the threshold for the growth of crops in toxic HM soils in mining areas and achieving further biological remediation.

Trace elements in aquatic products from Shenzhen, China and their implications for human exposure

Aquatic organisms in industrially polluted areas can accumulate large quantities of heavy metals. To assess the resulting health risks, 11 trace elements in 184 aquatic products representing 14 species of fish, crustaceans, and bivalves collected from Shenzhen, China were determined. Aluminum (Al), chromium (Cr), nickel (Ni), selenium (Se), antimony (Sb), manganese (Mn), copper (Cu), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) were determined by inductively coupled plasma mass spectrometry. The pollution levels of each product and the human health risk resulting from their consumption were then assessed. The concentrations of As in 57 % of samples and Cd in 11 % of samples exceeded the upper limits stipulated by the Chinese National Food Safety Standards (GB 2762-2017), which was mainly due to high concentrations of trace elements in crustaceans and bivalves. The Nemerow integrated pollution index indicated that the aquatic products accumulated high levels of As and Cd. Health risk assessments using the target hazard quotient (THQ) and hazard index (HI) suggested that As and Cd exposure due to consumption of aquatic products presents a potential health risk for residents of Shenzhen.

Recent applications of atomic spectroscopy coupled with magnetic solid‐phase extraction techniques for heavy metal determination in environmental samples: A review

AbstractAtomic spectroscopy is the most popular approach to determine the presence of heavy metals in the environment. Heavy metals are potentially toxic and have various negative effects on many living organisms, including humans. With the rapid increase in the variety of industries and human activities, large amounts of heavy metals are released into the atmosphere, water, and soil. Heavy metal analysis of environmental samples is very important for determining the exposure limits. Environmental samples are highly complex matrices, and various sample preparation techniques have been developed for the extraction of heavy metals from them, including magnetic solid‐phase extraction (MSPE). The use of MSPE in heavy metal analysis has recently gained significant attention owing to a number of advantages. MSPE technique overcomes main issues such as phase separation, handling, and column packing. The use of magnetic adsorbents in sample preparation has grown over the past few years, making MSPE a promising technique for sample preparation. The objective of this review article is to provide the latest applications of MSPE coupled with atomic spectroscopy for heavy metal determination in environmental samples. In addition, new magnetic adsorbents and their analytical merits are emphasized.

Remediation of Heavy Metals in Polluted Water by Immobilized Algae: Current Applications and Future Perspectives

The progression of urban industrialization releases large quantities of heavy metals into water, resulting in the severe heavy metal contamination of the aquatic environment. Traditional methods for removing heavy metals from wastewater generally have varying removal efficiencies, whereas algae adsorption technology is a cost-effective and sustainable bioremediation technique. A green technology that immobilizes algae through a carrier to improve biosorbent’s stability and adsorption performance is immobilization technology. The purpose of this review is to study the optimization strategy of the immobilization of algae for the bioremediation of heavy metals and to comprehensively analyze immobilized algae technology in terms of sustainability. The analysis of the mechanism of heavy metal removal by immobilized algae and the parameters affecting the efficiency of the biosorbent, as well as the approach based on life cycle assessment and economic analysis, allowed the identification of the optimization of the adsorption performance of immobilized algae. This provides a theoretical basis for the practical application of algal bioremediation.

Preparation and characterization of mortar specimens based on municipal solid waste incineration fly ash-activated slag

Municipal solid waste incineration fly ash (MSWIFA) contains a large amount of heavy metals, inhibiting resource utilization. This study used MSWIFA as an alkali activator and ground-granulated blast-furnace slag (GGBS) as a precursor to prepare the MSWIFA GGBS binder. Based on this, used the iron tailing sand instead of natural river sand as fine aggregate prepared mortar specimens by cooperative compression molding. Compressive strength, bulk density, water absorption, and heavy metal leaching tests were conducted and combined with micro XRD, FTIR, and SEM examinations to characterize the mortar specimens. The results show that the optimal MSWIFA: GGBS was 2:8. It was also found that increasing the molding pressure was beneficial to strength development. Compared to the specimens without the application of molding pressure, the 3 d and 28 d strength values increased by 148.6 and 122.2%, respectively, after the application of 35 MPa molding pressure. The reason is that the pressure effect can increase the cohesion of the particles, promote the hydration reaction to proceed, and the hydration products increase to fill the pores, increase the structural compactness and promote strength development. The resource utilization of MSWIFA must be guaranteed not to produce environmental pollution simultaneously. For this reason, the heavy metal leaching test was conducted on 28 d mortar specimens, and the results showed that the leaching rates of Zn, Pb, Cu, Cr, and Ni met the requirements of the Chinese Standard (GB16889-2008). The research results can provide a theoretical basis for the large-scale recycling of MSWIFA.

Investigation of the effect of acid sludge neutralization treatment on producing a sustainable eco-friendly additive for bituminous composites

ABSTRACT Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used ‘washing with water’ and ‘neutralization with quicklime’ methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the ‘washing with water’ method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge.

Insight into the subcellular mechanism of maximizing Cd accumulation in hyperaccumulator Solanum nigrum L. under the action of biodegradable chelating agent

Under the promotion of biodegradable chelating agents, hyperaccumulators can accumulate large amounts of heavy metals. However, in practical application, excessive accumulation of heavy metals will lead to the reduction of biomass, resulting in the reduction of heavy metal accumulation efficiency. Therefore, here we seek to investigate the dynamic process of vacuolar compartmentalization regulated by biological chelators, to provide guidance for improving the accumulation efficiency of heavy metals and alleviating the reduction of biomass. In this study, subcellular isolation was used to study the changes of enzyme activities, total cadmium (Cd), Cd2+, glutathione and reactive oxygen species (ROS) contents in protoplasts and vacuoles of leaf cells of Solanum nigrum L. The results indicate that vacuolar compartmentalization is a dynamic regulation process of continuous glutathione consumption. Under the promotion of biodegradable chelating agent N, N-bis glutamic acid (GLDA), more glutathione was induced and preferentially entered the vacuole to chelate and store Cd. Moreover, for large amounts of Cd accumulation, the insufficient supply of glutathione (GSH) preferentially maintains vacuolar homeostasis and causes redox damage outside the vacuole. These results showed that insufficient glutathione production led to the reduction of biomass. Therefore, in the practical application of GLDA, the consumption inside and outside the vacuole can be met by controlling the production of glutathione, so as to increase the efficiency of heavy metal accumulation.

Human health risk impact assessment of some heavy metals in groundwater around abandoned barite mine sites in parts of Benue state, Nigeria

An evaluation of the impacts of various heavy metals in the water on the hazard to human health was undertaken to ascertain whether the water from hand-dug wells close to abandoned barite mines in the research region was safe for human consumption. Analyses of the health risks connected to heavy metal exposure in humans through diet, skin absorption, inhalation, and ingestion are frequently used to assess these concerns. Chromium (Cr), Cadmium (Cd), Barium (Ba), Manganese (Mn), Lead (Pb), Arsenic (As), Nickel (Ni), and Zinc were evaluated for the research area's Chronic Daily Intake (CDI), Hazard Quotients (HQ), and Hazard Index (HI) (Zn). Four (4) water samples from hand-dug wells close to abandoned barite mining sites were tested for heavy metals. The Chronic Daily Intake (CDI), Hazard Quotient (HQ), and Hazard Index (HI) for adults and children were calculated using non-carcinogenic risks. The skin, the lungs, and the lips are the three different entry points for exposure. Calculate the exposure as if it were a chronic daily use. Hazard Index (HI) values for all of the PTEs (Cr, Cd, Ba, Mn, Pb, As, Ni, and Zn) evaluated in this study ranged from 7.78x10-5 to 4.97x10-2 in the water from the hand-dug wells. The findings suggest that a non-carcinogenic adverse health risk threshold of 1 is appropriate. Prolonged exposure to low quantities of heavy metals may result in mortality, deformities, delayed development, and diminished fertility. Organs may be quickly eliminated by acute exposure to large amounts of heavy metals.

MSW pyrolysis volatiles’ reforming by incineration fly ash for both pyrolysis products upgrading and fly ash stabilization

The effective disposal of municipal solid wastes (MSW) and its incineration-derived fly ash (IFA), which contains large amounts of heavy metals (HMs) and chlorine (Cl), is an urgent task. In this study, IFA was used to reform MSW pyrolysis volatiles within 500–800 °C. The changes of reformed pyrolysis products, the migration characteristics of HMs and Cl between IFA and pyrolysis products were investigated. The results indicated that the O- and Cl-containing compounds in pyrolysis oil tended to decrease, light hydrocarbons and its calorific value increased accordingly after reforming; more CH4 and H2 gases were produced concurrently. The increase in reforming temperature enhanced these trends. The IFA absorbed Cl from volatiles during reforming, which reduced HCl in the gas product. The toxicity equivalent (TEQ) of PCDD/Fs in IFA decreased dramatically from 0.47 μg/kg to 0.0055 μg/kg after reforming at 500 °C, and it decreased with increasing reforming temperature. Some of the HMs’ concentrations in the used IFAs increased, but their leaching capacity all decreased significantly at 800 °C except for Cr. The used IFA at 800 °C (IFA-800) corresponded to the lowest HMs leaching concentrations and could meet the landfill requirements; while the used IFA at 500 °C (IFA-500) corresponded to the maximum carbon deposition of 14.63 wt%, providing the energy source for its melting. Therefore 800 °C was recommended for harmless disposal of IFA, and 500 °C was better for a further melting of IFA., The contamination of pyrolysis liquid caused by inorganic Cl-containing compounds at 500 and 800 °C with much lower levels than the original. This study showed the hazardous properties of IFA can be dampened after interacting with MSW pyrolysis volatiles within the tested temperature range, and provided a good chance for the simultaneous disposal of IFA and recovery of high-quality MSW pyrolysis products.